156 Questions
What is the primary function of the components in a compression system?
To control the pressure and flow of the gases
What type of drive is commonly used for continuous service in compressors of all sizes?
Electric motor drive
What is the purpose of reduction gears in electric motor drives?
To reduce the compressor speed when the electric motor speed is too high
What type of fuel is used to power gas turbines in natural gas pipelines?
Natural gas from the pipeline
What is the typical application of internal combustion engine drives?
Emergency compressors during power failures
How are compressors driven by internal combustion engines typically connected?
Through a flywheel and V-belts
What is the main reason for installing shaft seals in compressors?
To prevent or minimize leakage of compressed gases
What type of seal is commonly used in air compressors?
Labyrinth seal
What is the primary function of the peaks in a labyrinth seal?
To maintain a close clearance to the shaft
What is the main advantage of carbon ring seals?
They have minimal compressed gas leakage
How does a liquid film seal work?
By creating a thin liquid film between the seal and the shaft
In which applications are liquid film seals typically used?
Hydrocarbon, refrigeration, and fertilizer applications
What is the main purpose of oil in mechanical seals?
To reduce wear and heat generation
What is the main advantage of dry gas seals?
They solve the problems involved with seal oil in centrifugal compressors
What is the purpose of the sealing gas in a dry gas seal?
To prevent leakage of the process gas
What is the main difference between a single and a double dry gas seal?
The direction of leakage
What is the purpose of oil-free packing rings in oil-free reciprocating gas compressors?
To provide maximum oil leakage containment
What type of bearings are commonly used in smaller compressors?
Sleeve/shell bearings with bronze material
What is the purpose of lubricating oil in a compressor?
To provide a film between surfaces
What is the main difference between external and internal lubrication?
The location of the lubrication
How is lubrication provided in small single-acting reciprocating compressors?
By a splash system
What is an advantage of dynamic compressors?
They do not require internal lubrication
How is lubrication provided in sliding vane rotary compressors?
By a pressure lubricator
What is the purpose of the pump in the pressure system of lubrication?
To deliver lubricant under pressure
What is the purpose of the splash system in lubrication?
To splash lubricant onto the cylinder walls and bearings
What is the purpose of the mechanical lubricator in internal lubrication?
To feed lubricant directly to the cylinder walls
What is the primary purpose of intercoolers and aftercoolers in air compressors?
To remove heat generated during compression and friction
What happens to the air when it passes through the intercoolers and aftercoolers?
The air becomes cooler and drier
What is the purpose of the pulley with large fan blades in Figure 4?
To increase the airflow over the fins of the intercoolers and aftercooler
What is the primary reason for removing water vapor from the compressed air?
To prevent water hammer or damage from freezing
What is the advantage of using intercoolers in air compressors?
They reduce the power required to compress the air
What is the purpose of the thermometer on the discharge air side of the intercoolers?
To measure the air temperature
What is the type of heat exchanger used in intercoolers and aftercoolers?
Shell and tube type
What is the purpose of the cyclone separator in the aftercooler?
To remove condensed moisture and other particles from the air stream
What is the advantage of using air-cooled intercoolers and aftercoolers?
They are typically used when the compressor itself is air-cooled
What is the purpose of the safety valve in the intercoolers?
To prevent over-pressurization of the intercoolers
What is the primary purpose of an air dryer in a compressed air system?
To remove moisture from the air
What type of substances are used in air dryers to attract moisture from the air?
Solid adsorbents
Why is it necessary to regenerate an adsorbent in an air dryer?
To remove the adsorbed moisture
What is the purpose of the second heat exchanger in a refrigerated air dryer?
To condense water and oil vapors
What is the function of an air receiver in a compressed air system?
To act as a reservoir and dampen pulsations in the discharge pressure
What is a common problem that can occur in air receivers if not properly maintained?
Corrosion and weakening of the vessel material
What is the purpose of a safety valve in an aftercooler?
To prevent overpressure
What is the difference between adsorbents and absorbents?
Adsorbents attract moisture by surface, while absorbents attract moisture by volume
What is the purpose of separators in an aftercooler?
To separate moisture from the air
What is the purpose of a refrigeration heat exchanger in a refrigerated air dryer?
To condense water and oil vapors
Why should the interior of an air receiver be thoroughly ventilated after opening?
To avoid accumulation of carbon monoxide gas
What is the purpose of a pressure relief valve in an air receiver?
To prevent overpressure conditions in the system
What is the primary function of a check valve in a compressed air system?
To prevent high-pressure air from flowing back into the compressor
Why are instruments such as pressure gauges and thermometers installed in a compressed air system?
To indicate variations from normal operation
What is the purpose of a compressor control system?
To vary the compressor output to suit load requirements
What is the advantage of using a start and stop control method for compressor control?
It is suitable for use with electric motor driven units
What is the purpose of an unloader in a compressed air system?
To unload the compressor during startup
What is the purpose of a pressure switch in a compressed air system?
To control the start and stop of the compressor
Why is it necessary to install safety valves at various points in a compressed air system?
To prevent overpressure conditions in the system
What is the purpose of a thermometer in a compressed air system?
To measure the temperature of the air in the system
What is the primary benefit of the reduced pressure in the pipe during the start of the compressor?
Decreases the load on the compressor
What is the purpose of the pilot type unloader in the Load/Unload Control method?
To vary the output from the compressor according to the air demand
How does the pilot valve operate in the Load/Unload Control method?
It does all of the above
What is the purpose of the Variable Speed Control method?
To maintain the system pressure at a constant value
What is the purpose of the Dual Control method?
To match compressor output to system demand
What is the purpose of the protective controls in a compressor?
To protect the compressor from damage or catastrophic failure
What is the condition that triggers the automatic shutdown of a two-stage compressor?
High lubricating oil temperature
What is the typical application of the Load/Unload Control method?
All of the above
What is the function of the spring in the pilot valve?
To hold the piston down on its seat
What is the effect of reducing the compressor speed in the Variable Speed Control method?
The receiver pressure increases
What is the primary purpose of reduction gears in electric motor drives?
To reduce the compressor speed when the electric motor speed is too high
What is the typical application of gas turbine drives?
To drive large centrifugal compressors that re-pressurize natural gas in pipelines
What is the common feature of electric motors used to drive compressors?
They are connected directly to the compressor shaft
What is the primary function of the components in a compression system?
All of the above
What is the typical application of internal combustion engine drives?
To drive emergency compressors that operate during power failures
What is the common feature of gas turbines used to drive compressors?
They are fueled directly from the natural gas pipeline
What is the primary function of the bearings in a compressor?
To reduce friction and wear of the moving parts
What is the main advantage of using pressure lubrication in compressors?
It provides a more consistent oil supply
In which type of compressors is internal lubrication not required?
Dynamic compressors
What is the purpose of the crankcase in a compressor?
To store oil for lubrication
What is the primary function of the oil wipers in oil-free packing ring seals?
To remove oil from the cylinder walls
What is the main difference between external and internal lubrication?
The location of lubrication
What is the purpose of the pump in the pressure system of lubrication?
To deliver oil to the bearings under pressure
What is the primary function of the mechanical lubricator in internal lubrication?
To deliver oil to the cylinder walls
What is the purpose of the deflectors in oil-free packing ring seals?
To direct oil to the oil wipers
What is the main advantage of using ball and tapered roller bearings in compressors?
They are more durable
What is the primary reason for using oil-free compressors in the food processing and medical industries?
To minimize the risk of contamination
What is the effect of not removing water vapour from the air in a compressed air system?
Water hammer or damage from freezing in pipelines
What is the purpose of the fins on the intercoolers and aftercoolers?
To increase the surface area for heat exchange
What is the function of the pressure relief valve on the discharge of the first stage in Figure 4?
To prevent over-pressurization of the system
What is the advantage of using multistage compressors in oil-free compressors?
To attain the required pressure
What is the primary purpose of shaft seals in compressors?
To minimize leakage and prevent safety and environmental hazards
What is the purpose of the thermometer on the cooling water side of the intercoolers?
To measure the temperature of the cooling water
What is the effect of not condensing and removing oil vapour from the air in a compressed air system?
Detrimental effect on air-operated instruments and increased risk of explosion
What is the mechanism by which labyrinth seals prevent gas leakage?
By trapping the gases through the forces within the labyrinth seal caused by the rotating shaft and the seal's design
What is the advantage of carbon ring seals over labyrinth seals?
They have minimal compressed gas leakage
What is the purpose of the cyclone separator in the aftercooler?
To remove condensed moisture and other particles from the air
What is the advantage of cooling the air during compression in oil-free compressors?
Increased efficiency of operation, reducing costs
What is the purpose of the oil film in liquid film seals?
To reduce wear and heat generation
What is the purpose of the safety valve in the intercoolers and aftercoolers?
To prevent over-pressurization of the system
What is the primary difference between mechanical seals and liquid film seals?
Mechanical seals use a small amount of oil for sealing and friction heat removal, while liquid film seals use a thin liquid film
What is the purpose of the dry gas seal in centrifugal compressors?
To solve the problems involved with seal oil in centrifugal compressors
What is the mechanism by which dry gas seals prevent gas leakage?
By injecting a sealing gas into the gap between the rotating and stationary rings
What is the primary advantage of dry gas seals over liquid film seals?
They do not require oil, which can be a safety hazard or incompatible with the process gas
What is the purpose of the tandem dry gas seal?
To prevent flammable and toxic gases from leaking to atmosphere
What is the primary difference between a single and a double dry gas seal?
A single dry gas seal is used for non-hazardous gases, while a double dry gas seal is used for toxic gas applications
What is the primary function of an air receiver in a compressed air system?
To act as a reservoir and dampen pulsations in the discharge pressure
What is the purpose of the second heat exchanger in a refrigerated air dryer?
To prevent further condensing of moisture from the dry air
Why is it necessary to regenerate an adsorbent in an air dryer?
To remove moisture from the adsorbent
What is the main difference between adsorbents and absorbents?
Adsorbents attract moisture from the air by surface, while absorbents attract moisture from the air by volume
What happens to the air when it passes through an air dryer filled with adsorbents?
The moisture is removed from the air, and the temperature of the air increases
What is the purpose of a safety valve in an air receiver?
To prevent the receiver from over-pressurizing
What is the purpose of separators in an aftercooler?
To remove oil and moisture from the air
What is the function of the refrigeration heat exchanger in a refrigerated air dryer?
To remove moisture from the air
What happens to the adsorbent when it becomes saturated?
It is taken out of operation and heated to about 150°C to regenerate it
What is the purpose of inspecting and hydrostatically testing air receivers periodically?
To ensure the receiver is properly operating and to prevent corrosion
Why is it necessary to keep naked lights and other sources of ignition away from the air receiver?
Because carbon monoxide is a combustible gas
What is the purpose of the pressure relief valves in the air receiver?
To prevent overpressure conditions
What is the function of the check valve in the line between the compressor and the air receiver?
To prevent high-pressure air in the receiver from blowing back into the compressor
What is the purpose of the thermometer in the discharge line from the cylinders of a reciprocating compressor?
To indicate variations from normal operation
What is the purpose of the pressure gauge in the delivery side of the air compressor?
To indicate variations from normal operation
What is the advantage of the start and stop control method for compressor control?
It is only used on electric motor driven units
What is the function of the unloader in the compressor control system?
To unload the compressor during startup
Why is it necessary to install safety valves at various points in a compressed air system?
To prevent overpressure conditions
What is the purpose of the pressure regulators in the compressed air system?
To maintain a constant pressure in the system
What is the purpose of the instruments such as pressure gauges and thermometers in a compressed air system?
To indicate variations from normal operation
What is the primary benefit of using a Load/Unload Control method with a large compressor?
Reduced starts and stops of the compressor
What is the function of the pilot valve in the Load/Unload Control method?
To operate the compressor inlet valve unloader
In a Variable Speed Control method, what is the primary means of adjusting the compressor output to match system demand?
Varying the compressor motor speed
What is the primary purpose of the Dual Control method in compressor control?
To match compressor output to system demand
What is the primary function of the protective controls in a compressor system?
To protect the compressor from damage or catastrophic failure
What is the result of the pilot valve operating the compressor inlet valve unloader in the Load/Unload Control method?
The compressor inlet valve becomes completely ineffective
In a Variable Speed Control method, what is the effect of decreasing the compressor speed during low air demand?
The compressor reduces its energy consumption
What is the primary advantage of using a Load/Unload Control method with a compressor that runs at greater than 50% of the time?
Reduced wear and tear on the compressor
What is the primary purpose of the unloader in the Load/Unload Control method?
To unload the compressor during periods of low air demand
What is the condition that triggers the automatic shutdown of a two-stage compressor with automatic shutdown devices?
High lubricating oil temperature
What is the typical temperature reached near the end of the stroke in a compressor cylinder?
90°C
Why is it important to clean the water jackets and intercooler pipes regularly?
To prevent scale accumulation
What is the importance of the condition of the air entering a compressor?
It affects the operation of the compressor
When should the cooling water for cylinder jackets and heads be turned on?
Before the compressor is started
Why is it important to take frequent temperature readings of the water during compressor operation?
To detect any irregularities in the cooling system
What is the maximum temperature that may be reached in exceptional circumstances in a compressor cylinder?
200°C
What is the primary reason for drawing air from a clean source outside the engine room?
To reduce abrasion caused by lubricating oil and dust
What is the consequence of not cleaning air filters regularly?
Early replacement of parts and shutdowns
What is the purpose of listening for unusual noises during routine checks?
To detect developing problems before they become serious
How often should air intake filters be cleaned or replaced?
Weekly, depending on the quality of supply air
What is the purpose of checking differential pressures across filters, intercoolers, and aftercoolers?
To detect developing problems before they become serious
What is the purpose of analyzing oil samples from lubricating and seal oil reservoirs?
To detect wear on the compressor's components
What is the approximate temperature reached near the end of the stroke under normal conditions?
90°C
Why is it important to turn on the cooling water for cylinder jackets and heads before starting the compressor?
To prevent overheating
What can accumulate in the water jackets, intercooler pipes, and other water-cooled parts if cooling water with impurities is used?
Scale
What is the effect of scale accumulation on the heat transfer from the compressed air to the circulating water?
It reduces heat transfer
How often should the water-cooled parts be cleaned?
As often as necessary
What has a marked effect on the operation of a compressor and the extent to which its moving parts will need to be repaired or replaced?
The correct treatment of the air entering the compressor
What is the primary reason for drawing air from a clean source outside the engine room?
To minimize the amount of dust and contaminants entering the compressor
What is the effect of sticky accumulations forming behind the piston rings?
Interferes with the free action of the piston rings and impairs the piston seal
How often air filters need cleaning is influenced by which of the following factors?
Type and capacity of the filter, volume of air handled, and amount of dust in the atmosphere
What is the purpose of performing routine checks on the compressor and related equipment?
To detect developing problems before they become serious
What is the primary purpose of lubricating the linkage, pins, and slide bars of control valves?
To prevent wear and corrosion on the linkage and slide bars
What is the recommended practice for determining when a filter needs cleaning?
Consult the manufacturer's recommendations
Test your knowledge of compression systems and compressor drives in power engineering. This quiz covers auxiliary systems, equipment, and components that manage the compression process, including upstream and downstream considerations. Learn about compressor drives, electric motor drives, and more.
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